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Does anyone know if there is any company that makes high flow cat for an MK4 supra? Been looking online and can't find much. To be transparent, I'm not very knowledgeable in this topic.

I live in California and my area has been cracking down on modded cars recently. A friend of a friend who is also running catless just recently got pulled over in traffic because of tints. The cops noticed the "smell" that came his car. They did a visual inspection and he got state reff'd. I want to avoid this at all cost. I'm not trying to pass smog, but to lessen my chances of getting pulled over.

I have a single turbo with straight pipe setup. My Tanabe touring medallion exhaust is very quiet. I'm hoping to find something that could be bolt on versus welded, but I'm not opposed to welding.

Really appreciate it.
 

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I have a race-cat that was made by Random Technology to bolt into their MKIV-specific downpipe. Sadly they are no longer in business. I doubt you'll find anything in current production that is ready to bolt on. But it should be pretty straightforward to buy a universal 100 cell cat with pipe diameter to match your current downpipe, and have it welded in to the forward section of the DP.
 

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You'll probably have to get one custom made. I spent a fair amount of time looking a couple of years ago for the same reasons, and didn't find anything worth buying. I got lucky and found someone selling a DP on here with a gesi cat (very high flowing and expensive) welded in, and it feels almost as good as a catless downpipe.
 

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Thanks for the tip beezupra. I did not know about them. I have a Random Technology high flow cat that has been on my car for 17 years. Last year or so I get some P0420 codes about catalytic efficiency, so it's probably going out. I'm going to check this out...

 

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Discussion Starter #6
I have a race-cat that was made by Random Technology to bolt into their MKIV-specific downpipe. Sadly they are no longer in business. I doubt you'll find anything in current production that is ready to bolt on. But it should be pretty straightforward to buy a universal 100 cell cat with pipe diameter to match your current downpipe, and have it welded in to the forward section of the DP.
If I have a 6266 turbo, do you know if I can get away with a 300 cell cat? Also do you know if the high flow cat just goes over down pipe and mid pipe or do you have to cut them for the cat to fit?
 

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Discussion Starter #7
You'll probably have to get one custom made. I spent a fair amount of time looking a couple of years ago for the same reasons, and didn't find anything worth buying. I got lucky and found someone selling a DP on here with a gesi cat (very high flowing and expensive) welded in, and it feels almost as good as a catless downpipe.
Do you have any pictures? Would love to see your setup and do you know what model genzi that you have installed ?
 

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If I have a 6266 turbo, do you know if I can get away with a 300 cell cat? Also do you know if the high flow cat just goes over down pipe and mid pipe or do you have to cut them for the cat to fit?
Say the new cat is 9" long - then for sure you have to pick which 9" of your downpipe to cut out to make room in the length for the cat.

What makes you ask about 300 cell? IME, a 100 cell cat probably wouldn't pass a strict emissions test, but it is plenty to eliminate fumes.

In general, the lower the cell-count, the higher the flow of a cat. But I haven't kept up with what is going on with high-quality race cat technology in recent years. My guess is that a cheap/poor design 300 cell could be a real limitation for a 6266, but a high-qual serious product could be no problem. An interesting example of what is possible: I have a 2018 Porsche with OEM 600 cell cats. At least two performance companies have said their testing shows these OEM cats don't present any significant restriction up to 680 whp.
 

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Do you have any pictures? Would love to see your setup and do you know what model genzi that you have installed ?
I've got it on the car, so I can't get a picture of the whole thing, but here it is installed on the car. It looks like somebody just added it to a standard catless downpipe. I'll see if I can get some numbers off the cat the next time I'm under the car.

258170
 

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With a 3in catback like the Tanabe Touring Medallion, I'd have a Kook's 3in high flow cat welded into the downpipe. There's a decent variety of high flow 3in cats out there, pick anything and have a decent fab shop do it.


SARD and A'PEXi make bolt-on HFC's for Supras with the stock TT's.

These are for the Japanese market Supra TT, and the flange that bolts up to the turbos only suits the stock JDM spec turbos. The export/US spec turbos on the 2JZ-GTE has a different flange.
 

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GESI is the actual name of the company that makes high flow cats up to 6 inch inlet/outlet. If you get the super high HP ones you'll need to have an exhaust shop build the piping.


I am running these on my GS-F. They are EPA compliant to a certain HP range. Supra doesn't use them as I run E85 and it smells yummy. The GS-F was stinky without them.

Good luck.

Steve
 

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These are for the Japanese market Supra TT, and the flange that bolts up to the turbos only suits the stock JDM spec turbos. The export/US spec turbos on the 2JZ-GTE has a different flange.
Ah didn't know that, thanks for correcting
 
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